The DVD (digital versatile disc) Stream Recording system is defined in the DVD Stream Recording Specification (SR spec.), Version 0.9, and is designed to use rewritable and recordable DVD discs for recording any existing digital bitstreams, editing them and replaying them as bitstreams.
According to the SR spec., a Stream Object (SOB) is, in general, one recorded bitstream, i.e. one take, which is stored as a part of a Program Stream as described in e.g. ISO/IEC 13818-1, Systems (MPEG-2). A SOB is composed of one or more Stream Packs, each containing a pack header followed by a Stream Packet. A Stream Packet contains further header data and Application Packets (AP_PKT) to each of which an Application Timestamp (ATS) is assigned. These timestamps enable proper application packet delivery during playback.
On the SR disc, a Stream Object Unit (SOBU) is the basic unit of a SOB and consists of a constant amount of data, 64 Kbytes according to the SR specification. The Stream Object Units include above Application Packets. Neither the SOBU borders nor the Stream Pack border need to be aligned with Application Packet borders.
For data retrieval from the disc a Mapping List is used wherein to each Stream Object Unit a corresponding specific time duration is assigned.
One feature of the DVD Stream Recording Specification is the possibility of temporary erasure (TE) of a cell containing a part of a SOBU or up to several Stream Object Units, followed by either recovery or permanent erasure (PE) of the cell. In the case of permanent erasure, any complete Stream Object Units within the cell can be freed for re-use. A cell can start or end at any application packet.
To each usable side of a disc an information file is assigned, the content of which is stored in a memory, e.g. a RAM, that is part of the streamer device.